Turn table and optical disk using the turn table

ABSTRACT

A turn table for mounting an optical disk without occurrence of eccentricity including: a fixed portion ( 48 ) fitted in a centre hole of the optical disk; a movable portion ( 50 ) fitted in the centre hole with the fixed portion ( 48 ) as a reference to be elastically deformed to correct eccentricity when the optical disk is mounted; a shaft portion ( 42 ) molded integral with the fixed portion ( 48 ) and into which is inserted a drive shaft ( 14   a ) of a drive motor for rotating a turn table ( 12 ) continuously; and a plate spring ( 60 ) for returning, when the optical disk is not mounted, the movable portion ( 50 ) from a position when the optical disk is mounted to a position when not mounted. The plate spring ( 60 ) is secured to the shaft portion ( 42 ) directly.

TECHNICAL FIELD

[0001] The present invention relates to a turn table for mounting adisk-like information recording medium thereon to rotate itcontinuously, and an optical disk using the turn table.

BACKGROUND ART

[0002] A turn table has been heretofore used in order to rotate anddrive a disk-like recording medium, for example, an optical disk such asa compact disk (CD), or a Digital Versatile Disk (DVD).

[0003] As a turn table for mounting an optical disk thereon to rotateand drive it, the turn table constituted as shown in FIG. 1 is used. Inthe turn table 1000, an optical disk D is fitted in a centring portion1002 formed with a centre hole 1001 in a centre portion of the turntable 1000 whereby the optical disk D is mounted on the turn table 1000.The centring portion 1002 is formed into a convergent trapezoid, and isformed, in the circumferential surface, with an elastic displacingelement 1004 elastically displaced in a diametrical direction and afixed element 1003 alternately there around. The inner peripheralsurface of the centre hole 1001 is pressed and supported by the elasticdisplacing element 1004 and placed in contact with the fixed element1003 to coincide the rotational centre with a rotational centre CL ofthe turn table 1000, and the optical disk D is mounted on the turn table1000.

[0004] A magnet 1005 is provided on the centring portion 1002 of theturn table 1000. The magnet 1005 magnetically attracts a chuckingportion not shown to hold the optical disk D in cooperation with theturn table 1000. A yoke 1006 is provided on the lower side of the magnet1005. The centring portion 1002 is secured to the turn table 1000 bypressing, and the turn table 1000 is mounted on a drive shaft 1008 of aspindle motor 1007 by pressing. The elastic displacing element 1004 forcarrying out the centring operation of the optical disk D provided andmounted on the centring portion 1002 is formed of a creepless materialsuch as PEI (poly ether imido) which is hard to produce the creepingphenomenon in order to prevent the creeping phenomenon from occurring inthe state that the optical disk D is mounted not to return to theoriginal state.

[0005] The turn table 1000 heretofore used has the construction in whichthe centring portion 1002 is pressed into the centre portion and pressedinto the drive shaft 1008 to mount it. That is, since the centringportion 1002 and the turn table 1000 are formed from a separate member,not only assembling is difficult but also mounting aimed at centring forallowing the centre of the centring portion 1000 to coincide with thecentre of the drive shaft 1008 is difficult.

[0006] There is a further problem that since the a creepless materialsuch as PEI (poly ether imido) is high in molding temperature, injectionmolding of the centring portion 1002 cannot be carried out in the statethat the magnet 1005 is put into a molding mold. When the magnet 1005 isexposed to the high temperature atmosphere, demagnetization occurs, andtherefore, the centring portion 1002 cannot be molded with the magnet1005 inserted. Therefore, the magnet 1005 is fixed by adhesion after thecentring portion 1002 has been molded. Since such a magnet 1005 isadhered, the assembling step of the centring portion 1002 becomescomplex, leading to the higher cost, and further posing a problem alsoin reliability in term of assembly.

[0007] Further, when the optical disk is mounted on the turn table androtated continuously, it is also necessary to prevent the optical diskfrom slipping with respect to the turn table. That is, the optical diskneed be rotated and driven integral with the turn table.

DISCLOSURE OF THE INVENTION

[0008] It is an object of the present invention to provide a novel turntable and an optical disk device using the turn table, which solves thetechnical problem noted above with respect to the conventional turntable.

[0009] It is a further object of the present invention to provide a turntable and an optical disk device using the turn table in which when adisk-like information recording medium is mounted, correction ofeccentricity of the information recording medium can be carried outpositively by a simple constitution.

[0010] It is another object of the present invention to provide a turntable and an optical disk device using the turn table capable ofmounting a disk-like information recording medium so as to be rotatedand driven positively integrally while suppressing occurrence ofeccentricity when the disk-like information recording medium is mounted.

[0011] In the turn table according to the present invention, a fixedportion is fitted into a centre hole of a disk-like informationrecording medium. A movable portion corrects eccentricity when thedisk-like information recording medium is mounted. A return assistingmember has a function in which when the disk-like information recordingmedium is not mounted, the movable portion is returned from a positionwhen the disk-like information recording medium is mounted to a positionwhen the disk-like information recording medium is not mounted. By theprovision of this constitution, when the disk-like information recordingmedium is mounted, the movable portion is able to correct eccentricityof the disk-like information recording medium. Moreover, the returnassisting member is able to return the movable portion from a positionwhen the disk-like information recording medium is mounted to a positionwhen the disk-like information recording medium is not mounted. Fromthis, the movable portion is able to correct eccentricy positively whenthe disk-like information recording medium is mounted.

[0012] By the provision of the return assisting member, a portionincluding the movable portion need not to use quality of a creeplessmaterial for preventing the creeping phenomenon unlike prior art, but isable to use synthetic resin having been used widely heretofore as amaterial for constituting a turn table. From this, since a specialquality like a creeping material is not used, the cost can be reduced.Moreover, since the return assisting member is secured to the shaftportion, a special portion is not necessary for securing the returnassisting member, and the return assisting member can be secured to theshaft portion directly, for example, by pressing or adhesion. From this,the construction is simple, and the cost can be reduced.

[0013] In the turn table according to the present invention, the movableportion has elastic displaceable elements, a plurality of which arearranged at equal angles about a rotational centre shaft. Since theplurality of elastic displaceable elements are arranged at equal anglesabout a rotational centre shaft, it is possible to correct eccentricityof the disk-like information recording medium mounted on the centringportion positively at any position.

[0014] Further, the turn table according to the present invention has amember for chucking the disk-like information recording medium, and amagnet for attracting the chucking member magnetically, the disk-likeinformation recording medium being held detachably between the magnetand the chucking member. The magnet provided on the turn table attractsthe chucking member to hold the disk-like information recording mediumdetachably.

[0015] Further, a turn table for mounting a disk-like informationrecording medium to continuously rotate it according to the presentinvention comprises a fixed portion having a hole for fitting a shaft ofa motor for continuously rotating the turn table and fitted in a centrehole of the disk-like information recording medium, a movable portionfitted in an inner peripheral edge with the fixed portion as s referenceto be elastically deformed to correct eccentricity when the disk-likeinformation recording medium is mounted, and a return assisting memberin which when the disk-like information recording medium is not mounted,the movable portion is returned from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted.

[0016] In the turn table, the fixed portion is fitted in a centre holeof the disk-like information recording medium. The movable portioncorrects eccentricity when the disk-like information recording medium ismounted. The return assisting member has a function for returning themovable portion from a position when the disk-like information recordingmedium is mounted to a position when the disk-like information recordingmedium is not mounted. With this, when the disk-like informationrecording medium is mounted on the turn table, the movable portion isable to correct eccentricity of the disk-like information recordingmedium. Moreover, the return assisting member is able to return themovable portion from a position when the disk-like information recordingmedium is mounted to a position when the disk-like information recordingmedium is not mounted. With this, the movable portion is able to correcteccentricity positively when the disk-like information recording mediumis mounted.

[0017] By the provision of the return assisting member, a portionincluding the movable portion need not to use quality of a creeplessmaterial for preventing the creeping phenomenon unlike prior art, but isable to use synthetic resin having been used widely heretofore as amaterial for constituting a turn table. From this, since a specialquality like a creeping material is not used, the cost can be reduced.Further, the fixed portion has a hole for fitting a drive shaft of adrive motor, and the return assisting member can be secured to the driveshaft of the drive motor directly. From this, since the return assistingmember need not to prepare a special portion but may be secured to thedrive shaft directly, the construction is simple, and the cost can bereduced.

[0018] The movable portion provided on the turn table comprises elasticdisplaceable elements, a plurality of which are arranged at equal anglesabout a rotational centre shaft. Since the plurality of elasticdisplaceable elements are arranged at equal angles about a rotationalcentre shaft, the movable portion is possible to correct eccentricity ofthe disk-like information recording medium positively at any position.

[0019] Also in this turn table, it has a member for chucking a disk-likeinformation recording medium, and a magnet for attracting the member forchucking magnetically; and the disk-like information recording medium isheld between the magnet and the member for chucking detachably. Themagnet provided on the turn table attracts the chucking member to holdthe disk-like information recording medium detachably.

[0020] Further, according to the present invention, there is provided anoptical disk device having a turn table for mounting a disk-likeinformation recording medium to rotate it continuously, the turn tableprovided on the device comprising: a fixed portion fitted in a centrehole of the disk-like information recording medium; a movable portionfitted in the centre hole with the fixed portion as a reference to beelastically deformed to correct eccentricity when the disk-likeinformation recording medium is mounted; a shaft portion molded integralwith the fixed portion and into which is inserted a drive shaft of adrive motor for rotating the turn table continuously; and a returnassisting member for returning, when the disk-like information recordingmedium is not mounted, the movable portion from a position when thedisk-like information recording medium is mounted to a position when thedisk-like information recording medium is not mounted, the returnassisting member being secured to the shaft portion directly.

[0021] The turn table used for the optical disk device is fitted in thecentre hole of the disk-like information recording medium. The movableportion corrects eccentricity when the disk-like information recordingmedium is mounted. The return assisting member has a function forreturning, when the disk-like information recording medium is notmounted, the movable portion from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted. By the provision of thisconstitution, when the disk-like information recording medium ismounted, the movable portion is able to correct eccentricity ofdisk-like information recording medium. Moreover, the return assistingmember is able to return, when the disk-like information recordingmedium is not mounted, the movable portion from a position when thedisk-like information recording medium is mounted to a position when thedisk-like information recording medium is not mounted. From this, themovable portion is able to correct eccentricity positively when thedisk-like information recording medium is mounted.

[0022] By the provision of the return assisting member, a portionincluding the movable portion need not to use quality of a creeplessmaterial for preventing the creeping phenomenon unlike prior art, but isable to use synthetic resin having been used widely heretofore as amaterial for constituting a turn table. From this, since a specialquality like a creeping material is not used, the cost can be reduced.Further, since the return assisting member is secured to the shaftportion, a special portion for securing the return assisting member isnot necessary, but can be secured to the drive shaft directly, forexample, by pressing or adhesion. From this, the construction is simple,and the cost can be reduced.

[0023] In the turn table used for the optical disk device according tothe present invention, the movable portion comprises elasticdisplaceable elements, a plurality of which are arranged at equal anglesabout a rotational centre shaft. Since the plurality of elasticdisplaceable elements are arranged at equal angles about a rotationalcentre shaft, the movable portion is possible to correct eccentricity ofthe disk-like information recording medium mounted on the centringportion positively at any position.

[0024] Further, the turn table has a member for chucking a disk-likeinformaion recording medium, and a magnet for attracting the member forchucking magnetically; and the disk-like informaion recording medium isheld detachably between the magnet and the member for chucking. Themagnet provided on the turn table attracts the chucking member to holdthe disk-like informaion recording medium detachably.

[0025] Further, according to the present invention, there is provided anoptical disk device provided with a turn table for mounting a disk-likeinformation recording medium to rotate it continuously, comprising: afixed portion having a hole for fitting a shaft of a motor for rotatingthe turn table continuously and fitted in a centre hole of the disk-likeinformation recording medium; a movable portion fitted in the centrehole with the fixed portion as a reference to be elastically deformed tocorrect eccentricity when the disk-like information recording medium ismounted; and a return assisting member for returning, when the disk-likeinformation recording medium is not mounted, the movable portion from aposition when the disk-like information recording medium is mounted to aposition when the disk-like information recording medium is not mounted.A centring portion constituting the fixed portion of the turn table isprovided with a hole for fitting a drive shaft of a drive motor forrotating the turn table continuously, and the return assisting member issecured to the drive shaft of the drive motor directly.

[0026] In the optical disk device, the fixed portion of the turn tableis fitted in the centre hole of the disk-like information recordingmedium. The movable portion corrects eccentricity when the disk-likeinformation recording medium is mounted. The return assisting member hasa function for returning, when the disk-like information recordingmedium is not mounted, the movable portion from a position when thedisk-like information recording medium is mounted to a position when thedisk-like information recording medium is not mounted. Thereby, when thedisk-like information recording medium is mounted on the turn table, themovable portion is able to correct eccentricity of the disk-likeinformation recording medium. Moreover the return assisting member isable to return the movable portion from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted. From this, the movableportion is able to correct eccentricity positively when the disk-likeinformation recording medium is mounted.

[0027] By the provision of the return assisting member, a portionincluding the movable portion need not to use quality of a creeplessmaterial for preventing the creeping phenomenon unlike prior art, but isable to use synthetic resin having been used widely heretofore as amaterial for constituting a turn table. From this, since a specialquality like a creeping material is not used, the cost can be reduced.Further, the fixed portion has a hole for fitting the drive shaft of thedrive motor, and the return assisting member can be secured to the driveshaft of the drive motor directly. Thereby, since the return assistingmember need not prepare a special portion, but may be secured to thedrive shaft directly, the construction is simple and the cost can bereduced.

[0028] The movable portion provided on the turn table comprises elasticdisplaceable elements, a plurality of which are arranged at equal anglesabout a rotational centre shaft. Since the plurality of movable portionsare arranged at equal angles about a rotational centre shaft, themovable portion is possible to correct eccentricity of the disk-likeinformation recording medium positively at any position.

[0029] Also the turn table further has a member for chucking a disk-likeinformation recording medium, and a magnet for attracting the member forchucking magnetically; and the disk-like information recording medium isheld detachably between the magnet and the member for chucking. Themagnet provided on the turn table attracts the chucking member to holdthe disk-like information recording medium detachably.

[0030] Further, according to the present invention, there is provided aturn table for mounting a disk-like information recording medium torotate it continuously, comprising: a fixed portion fitted in a centrehole of a disk-like information recording medium; a movable portionfitted in the centre hole with the fixed portion as a reference to beelastically deformed to correct eccentricity when the disk-likeinformation recording medium is mounted; a return assisting member forreturning, when the disk-like information recording medium is notmounted, the movable portion from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted; and a slip preventiveportion provided on the return assisting member to come in contact withthe disk-like information recording medium mounted to thereby preventthe disk-like information recording medium from slipping.

[0031] The fixed portion provided on the turn table is fitted in thecentre hole of the disk-like information recording medium. The movableportion corrects eccentricity when the disk-like information recordingmedium is mounted. The return assisting member has a function forreturning, when the disk-like information recording medium is notmounted, the movable portion from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted. The slip preventive portionprevents, with which the disk-like information recording medium mountedcomes in contact, the disk-like information recording medium fromslipping. By the provision of such a constitution as described, themovable portion is able to correct eccentricity of the disk-likeinformation recording medium when the disk-like information recordingmedium is mounted on the turn table. Moreover, the return assistingmember is able to return, when the disk-like information recordingmedium is not mounted, the movable portion from a position when thedisk-like information recording medium is mounted to a position when thedisk-like information recording medium is not mounted. From this, themovable portion is able to correct eccentricity positively when thedisk-like information recording medium is mounted.

[0032] The turn table according to the present invention is providedwith the slip preventive portion to thereby enable positive integrationof the disk-like information recording medium mounted without slippingto rotate and drive it.

[0033] Furthermore, according to the present invention, there isprovided an optical disk device having a turn table for mounting adisk-like information recording medium to rotate it continuously, theturn table used in the device comprising: a fixed portion fitted in acentre hole of the disk-like information recording medium; a movableportion fitted in the centre hole with the fixed portion as a referenceto be elastically deformed to correct eccentricity when the disk-likeinformation recording medium is mounted; a return assisting member forreturning, when the disk-like information recording medium is notmounted, the movable portion from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted; and a slip preventiveportion provided on the return assisting member to prevent, with whichthe disk-like information recording medium mounted comes in contact, thedisk-like information recording medium from slipping.

[0034] The fixed portion provided on the turn table is fitted in thecentre hole of the disk-like information recording medium. The movableportion corrects eccentricity when the disk-like information recordingmedium is mounted. The return assisting member has a function forreturning, when the disk-like information recording medium is notmounted, the movable portion from a position when the disk-likeinformation recording medium is mounted to a position when the disk-likeinformation recording medium is not mounted. The slip preventive portionprevents , with which the disk-like information recording medium mountedcomes in contact, the disk-like information recording medium fromslipping. By the provision of such a constitution as described, themovable portion is able to correct eccentricity of the disk-likeinformation recording medium when the disk-like information recordingmedium is mounted on the turn table. Moreover, the return assistingmember is able to return, when the disk-like information recordingmedium is not mounted, the movable portion from a position when thedisk-like information recording medium is mounted to a position when thedisk-like information recording medium is not mounted. From this, themovable portion is able to correct eccentricity positively when thedisk-like information recording medium is mounted, and by the provisionof the slip preventive portion, the disk-like information recordingmedium mounted can be placed in positive integration without slipping torotate and drive it.

[0035] Further other objects of the present invention and the specificadvantages obtained by the present invention will be more apparent fromthe ensuing explanation of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a sectional view of a conventional turn table.

[0037]FIG. 2 is a perspective view showing an optical disk device havinga turn table according to the present invention.

[0038]FIG. 3 is a sectional view showing a turn table and a motor of theoptical disk device shown in FIG. 2.

[0039]FIG. 4 is an exploded perspective view showing a turn table, aplate spring and a motor of the optical disk device shown in FIG. 2.

[0040]FIG. 5 is a sectional view showing the turn table and the platespring shown in FIG. 4.

[0041]FIG. 6 is a plan view showing the turn table shown in FIG. 5.

[0042]FIG. 7 is a view showing that the plate spring be the assistingforce at the time of centring.

[0043]FIG. 8 is a bottom view of the turn table shown in FIG. 5.

[0044]FIG. 9 is a plan view of the plate spring shown in FIG. 4.

[0045]FIG. 10 is a sectional view showing another example of the turntable according to the present invention.

[0046]FIG. 11 is a plan view of the plate spring used for the turn tableshown in FIG. 10.

[0047]FIG. 12 is a plan view showing another example of the plate springused in the turn table shown in FIG. 10.

[0048]FIG. 13 is a sectional view showing a further example of the turntable according to the present invention.

[0049]FIG. 14 is a plan view of the plate spring used in the turn tableshown in FIG. 13.

[0050]FIG. 15 is an exploded perspective view showing still anotherexample of the turn table according to the present invention, FIG. 16 isa sectional view thereof, FIG. 17 is a plan view thereof, and FIG. 18 isa bottom view thereof.

[0051]FIG. 19 is a plan view showing the plate spring used in the turntable shown in FIG. 15.

[0052]FIG. 20A and FIG. 20B are respectively side views showing theenhancement of the load resistance of the turn table.

[0053]FIG. 21 is a sectional view showing a further example of the turntable according to the present invention.

[0054]FIG. 22 is a perspective view partly cutaway, FIG. 23A is a planview thereof, and FIG. 23B is a bottom view thereof.

[0055]FIG. 24 is a plan view showing the plate spring sued in the turntable shown in FIG. 21.

[0056]FIG. 25 is a plan view showing a part of the turn table shown inFIG. 21.

[0057]FIG. 26 is a sectional view taken on line A-A of FIG. 25.

[0058]FIG. 27 is a sectional view showing another example of a partcorresponding to the section taken on line A-A of FIG. 25.

[0059]FIG. 28 is a sectional view showing still another example of theturn table according to the present invention.

[0060]FIG. 29 is a sectional view showing a further example of the turntable according to the present invention.

[0061]FIG. 30 is a perspective view showing a part of the turn table ina cutaway form, and FIG. 31 is a plan view thereof.

BEST MODE FOR CARRYING OUT THE INVENTION

[0062] The turn table and the optical disk device using the turn tableaccording to the present invention will be explained hereinafterreferring to some embodiments.

[0063] It is noted that since the embodiments shown below are preferredembodiments of the present invention, technically preferred limitationsare noted. However, the present invention is not limited to theseembodiments unless there is a statement that particularly limits thepresent invention in the ensuing explanation.

[0064] First, an optical disk device using a turn table 1 according tothe present invention will be explained. In this optical disk device, aturn table 12, on which is detachably mounted an optical disk D such asa compact disk or DVD which is a disk-like information recording medium,is provided on one end of a base member 16, as shown in FIG. 2. The turntable 12 is mounted on a drive motor 14 mounted on the base member 16,and is rotated and driven by the drive motor 14.

[0065] In FIG. 2, a casing of the optical disk device 10 is not shown,but the base member 16 is encased in the casing. The base member 16 isprovided with a pick up feed mechanism 22 which supports an opticalpick-up 20 to feed/operate it in a direction of arrow X₁ or in adirection of arrow X₂ in FIG. 2. The pick up feed mechanism 22 isprovided with a drive motor 24 for feed-operating the optical pick up20. The driving force of the drive motor 24 is transmitted to a rack 34through a plurality of gears 26, 28, 30 and 32, and the rack 34, and therack 34 is move/operated to thereby feed/operate the optical pick up 20in a direction of arrow X₁ or in a direction of arrow X₂ in FIG. 2.

[0066] The optical pick up 20 has a function that for example, a laserbeam is irradiated on the read surface of the optical disk D mounted onthe turn table 12 to optically read information recorded in the opticaldisk D, or information is written in the optical disk D by a laser beamas necessary. The optical pick up 20 may be exclusive use for read onlythat only reads information of the optical disk D as mentioned above, ormay be of a recording and reproducing type capable of readinginformation or writing information in the optical disk D.

[0067] The turn table 12 according to the present invention used in theaforementioned optical disk device will now be described in detail withreference to FIGS. 3 and 4.

[0068] The turn table 12 according to the present invention has acentring portion 40 and a shaft portion 42, as shown in FIGS. 3 and 4,the centring portion 40 and the shaft portion 42 being formedintegrally. The centring portion 40 and the shaft portion 42 can beformed using synthetic resin, for example, such as polycarbonate. Asmaterial constituting the centring portion 40 and the shaft portion 42,any material having quality not to demagnetize the magnetic force of amagnet 44 may be used.

[0069] The turn table 12 has a centring portion 40, a receiving portion46, a fixed portion 48, and a plurality of movable portions 50. Thereceiving portion 46, the fixed portion 48, and the movable portions 50are formed by integral molding. The centring portion 40 is integral withthe shaft portion 2 as described above, but the shaft portion 42 isformed to be projected in an axial direction. The shaft portion 42 isformed in its centre with a shaft insert hole 42 a along the centreshaft CL, and a drive shaft 14 a of the drive motor 14 is pressed intothe shaft insert hole 42 a.

[0070] The magnet 44 is mounted integral with the centring portion 40.The magnet 44 is mounted so as to be buried into a concave portion 40 aformed ringwise on the outer peripheral side on the extreme end side ofthe centring portion 40. That is, the magnet 44 is mounted by subjectingto insert molding with respect to the centring portion 40. The magnet 44can be subjected to insert molding with respect to the centring portion40 because the centring portion 40 and the shaft portion 42 are formedof synthetic resin normally used without using special synthetic resinmaterial which is a conventional creepless material. Moreover, since thecentring portion 40 and the shaft portion 42 are formed of a materialnot to demagnetize the magnetic force of the magnet 44, the magnet 44 isable to sufficiently hold its own magnetic force.

[0071] A chucking portion 56 for holding the optical disk D togetherwith the turn table 12 is provided with a metal plate 58. The magnet 44magnetically attracts the metal plate 58 of the chucking portion 56 anda boss of the chucking portion 56 is fitted in an engaging concaveportion 40 c provided in the centre portion on the upper end side of thecentring portion 40 whereby the chucking portion 56 presses the opticaldisk D against the receiving portion 46 of the turn table 12 forchucking.

[0072] The centring portion 40 formed into a convergent trapezoid isformed with the fixed portion 48 as shown in FIGS. 4, 5 and 6. The fixedportion 48 is constituted by a part of a tapered outer peripheralportion of the centring portion 40. Further, for example, five movableportions 50 are formed at equal intervals in a peripheral direction onthe outer peripheral portion of the centring portion 40.

[0073] The fixed portion 48 is a portion for supporting an innerperipheral edge 46 of a centre hole H of the optical disk D, as shown inFIG. 3, and a plurality of movable portions 50 has a centring functionthat they are formed to be elastically displaceable, or elasticallymovable, elements long-cantilever supported along the outer peripheralsurface of the centring portion 40 to be elastically displaced tocoincide the rotational centre of the optical disk D with the centreshaft CL of the turn table 12.

[0074] Further, on the lower end side of the centring portion 40 isprovided a plate spring 60 as a return assisting member for returningthe elastically deformed movable portion 50 to an initial position, asshown in FIG. 3. The plate spring 60 is formed, for example, from a thinmetal sheet, and has a function that in the state that the optical diskD is mounted on the movable portion 50, the plate spring 60 iselastically deformed in a direction of arrow R1 in FIG. 3 together withthe movable portion 50, and when the optical disk D is removed from theturn table 12, the movable portion 50 is forcibly returned in adirection of arrow R2 in FIG. 3 so as to assume the initial state whenthe optical disk D is mounted shown in FIG. 5.

[0075] Incidentally, the movable portion 50 formed integral with thecentring portion 40 by mold molding of synthetic resin is provided, onthe free end side, with a vertical portion 50 a larger than a thicknessportion EF of the optical disk D, as shown in FIG. 7. On the extreme endside of the vertical portion 50 a is formed a stopping shoulder portion50 b for stopping the optical disk D inserted into the centring portion40. The outer peripheral diameter of a portion of the vertical portion50 a of a plurality of movable portions 50 provided in the centringportion 40 is formed to be larger than the inner peripheral diameter ofthe cenerter hall H to be a reference of the optical disk D. That is,the movable portion 50 is formed so that when the centring portion 40comes in engagement with the centre hole H of the optical disk D, themovable portion 50 may be elastically deformed by a fixed amount by theinner peripheral edge of the centre hole H, for example, in a directionof arrow R1 in FIG. 7 on the inner peripheral side shown by an arrow din FIG. 7.

[0076] When the movable portion 50 is elastically deformed in adirection of R1 in FIG. 7 by the optical disk D, the plate spring 60functioned as a return assisting member is pressed by a free end 50 c ofthe movable portion 50 and elastically deformed in a direction of arrowR3 in FIG. 7 in the same direction as the elastically deformingdirection of the movable portion 50. The plate spring 60 imparts theelastic force for returning the movable portion 50 to the initialposition when the optical disk D is mounted on the turn table 12 withthe centre hole H inserted into the centring portion 40.

[0077] When the optical disk D is pressed and elastically deformed bythe movable portion 50 formed by the molded body of synthetic resin, andremoved from the centring portion 40, the plate spring 60 forelastically returning the movable portion to the initial position isformed of metal, and therefore, is excellent in temperaturecharacteristic as compared with the movable portion 50 made of syntheticresin and is able to maintain the stabilized elastic force without beinggreatly affected by the change of temperature of the externalenvironment. The movable portion 50 is elastically displaced making useof the elastic force of the late spring 60 to thereby enable elasticdisplacement in the stabilized state so that the optical disk D ismounted positively on the centring portion 40 to enable accuratecentring to realized mounting to the turn table 12.

[0078] By the provision of the plate spring 60 for assisting the elasticdisplacement of the movable portion 50 for carrying out centringprovided integral with the centring portion made of synthetic resin, itis possible to prevent that the optical disk D is mounted on the turntable 12 as shown in FIG. 3, and when the state that the movable portion50 is elastically displaced in a direction of arrow R1 in FIG. 3 ismaintained for a long period of time, the creeping phenomenon occurs tofail to return to the initial position as shown in FIG. 5.

[0079] When assuming the state that the movable portion 50 cannot beelastically returned to the initial position, it is not possible toattain centring of the of the optical disk D by the centring portion 40.

[0080] In the present invention, after the movable portion 50 formed ofsynthetic resin has been elastically deformed and when the optical diskD is removed from the turn table 12 and thereby elastically returned inthe direction of arrow R2 in FIG. 3, the movable portion 50 is pressedand biased by the elastic forces of the plate spring 60 in theelastically displaced state, and therefore, the stabilized elasticreturning becomes enabled. By the provision of the plate spring 60 asdescribed, for the centring portion 40 including the movable portion 50,a conventional expensive synthetic resin material having a creeplessfunction is not used but a synthetic resin material heretofore used, forexample, a polycarbonate resin or the like can be used, to enablereduction in cost for manufacturing the turn table 20.

[0081] As described above, the centring portion 40 is molded ofsynthetic resin such as polycarbonate resin whereby the magnet 44provided on the centring portion 40 can be mounted integral with thecentring portion 40 simultaneously with molding of the centring portion40 when the centring portion 40 is molded. In this case, preferably, asynthetic resin material not to demagnetize the magnetic force of themagnet 44 is used for the cenrtering portion 40.

[0082] The plate spring 60 constituting the turn table 12 according tothe present invention is formed by punching a metal plate in the form ofa thin sheet, for example, such as stainless steel for a spring (SUS301-CSP, SUS 304-CSP) or bronze for a spring (C5210P-1/2H) as shown inFIG. 4. That is, the plate spring 60 is formed by punching a disk-likethin sheet metal plate by way of pressing or the like, a plurality of,for example, five support elements 62 are projected at equal intervalsin a peripheral direction on the outer peripheral side of a ring-likeportion 61 bored with a centre hole 61 a, and a single detent element 63is projected. The plate spring 60 is mounted on the bottom surface ofthe centring portion 40 by fitting the centre hole 61 a in the shaftportion 42 of the turn table 12.

[0083] It is noted that the ring-like portion 61 is formed in the innerperipheral surface thereof bored with a plurality of grooves 61 b, asshown in FIGS. 4 and 9. As described above, by the provision of thegrooves 61 b, when the ring-like portion 61 is fitted in the shaftportion 42, the element between the grooves 61 b is elasticallydisplaced to thereby enable firm mounting of the plate spring 60 on theshaft portion 42.

[0084] In the outer periphery of the ring-like portion 61 of the platespring 60, for example, five support elements 62 are formed so as to beprojected in a diametrical direction, as mentioned above. Each supportelement 62 has a function of elastically deformably supporting the lowerend of the movable portion 50 at a corresponding position. The supportelements 62 are formed to be projected, preferably, at equal angleintervals with respect to the ring-like portion 61. Each support element61 is formed substantially in the shape of T as shown in FIG. 9.Further, the single detent element 63 is formed between the supportelements 62, 62 adjacent to each other. The detent element 63 has afunction that it is engaged with an engaging projection 100 projected onthe lower end of the fixed portion 48 to attain detention of the platespring 60 with respect to the shaft portion 42 and to carry out axiallocating of the plate spring 60 and the shaft portion 41. FIG. 5 showsthe state that the detent 63 is fitted in the engaging projection 100.In the state that the detent 63 is fitted in the engaging projection 100as described, the plate spring 60 supports the lower end of the movableportion 50. It is noted that the engaging projection 100 attainsanti-slipping of the detent element 63 by melting and deforming theextreme end thereof as necessary.

[0085] Mounting of the plate spring 60 formed as described above on theshaft portion 42 is done by pressing the ring-like portion 61 into theshaft portion 42 through the centre hole 61 a, as shown in FIG. 4.Further, for attaining the anti-slipping of the plate spring 60 from theshaft portion 42, the ring-like portion 61 may be bonded to the shaftportion 42 by an adhesive.

[0086]FIG. 6 is a plan view of the turn table 12 according to thepresent invention, and FIG. 8 is a bottom view thereof. FIG. 6 showsfive movable portions 50, fixed portions 48 and receiving portions 46formed integral with the centring portion 40, and FIG. 8 shows fivemovable portions 50.

[0087] A further embodiment of the turn table according to the presentinvention will be explained with reference to FIGS. 10 to 12.

[0088] In the turn table 12, a plate spring is mounted on the shaftportion 42 by pressing the plate spring into the shaft portion 42 or bypressing and adhesion with respect to the shaft portion 42. In a platespring 160 used herein, a plurality of support elements 62 are projectedon the outer peripheral portion of the ring-like portion 61, as shown inFIG. 11. The support element 62 is formed substantially in the shape ofT, and five support elements are provided at equal intervals around theouter peripheral portion of the ring-like portion 61.

[0089] The thus formed plate spring 160 is mounted on the turn table 12by pressing the ring-like portion 61 into the shaft portion 42 or bypressing or adhesion with respect to the shaft portion 42, as shown inFIG. 10, and the free end of the movable portion 50 provided on thecentring portion 40 is supported by the support element 62.

[0090] Further, a plate spring 260 may be one formed as shown in FIG.12. In the plate spring 260 shown in FIG. 12, five support elements 262are formed at equal intervals around the outer peripheral portion of aring-like portion 261. These support elements 262 are formedsubstantially in the shape of T, and have a connecting portion 262 aprojected in a radial direction and an arched portion 262 b projectedaround the ringlike portion 61. The plate spring 260 is also mounted onthe turn table 12 by pressing the ring-like portion 261 into the shaftportion 42 or by pressing or adhesion with respect to the shaft portion42, as shown in FIG. 10, and the free end of the movable portion 50provided on the centring portion 40 is supported by the support element262. The plate spring 260 formed as shown in FIG. 12 is able to vary acontact position of the movable portion 50 with respect to the archedportion 262 b to a position around the direction indicated by an arrow Win FIG. 12 by varying a mounting position around the shaft portion 42.The contact position of the movable portion 50 with respect to thearched portion 262 b can be varied to thereby vary the support force forsupporting the movable portion 50 of the arched portion 262 b.

[0091] Still another embodiment of the turn table 12 according to thepresent invention will be explained with reference to FIGS. 13 to 14.

[0092] In this turn table 12, a part of a plate spring 360 is broughtinto engagement with an engaging projection 310 projected on the bottomside of the centring portion 40 so as to mount the plate spring 360 onthe turn table 12. In the plate spring360 used herein, five supportelements 362 are projected at equal intervals around the outerperipheral portion of a ring-like portion 361. An engaging element 364bored with an engaging hole 365 engaged with the engaging projection 310at the extreme end is formed to be projected between the supportelements 362, 362 adjacent to each other. The plate spring 360 ismounted on the turn table 12 by fitting the ring-like portion 361 in theshaft portion 42, and engaging an engaging hole 365 provided in theengaging projection 364 with the engaging projection 310. At this time,the extreme end of the engaging projection 310 is molten and deformed toenable attaining anti-slipping of the plate spring 360 from the shaftportion 42.

[0093] Another embodiment of the turn table 12 according to the presentinvention will be explained with reference to FIGS. 15 to 19.

[0094]FIG. 15 is an exploded perspective view showing a turn table 12and a motor 14 for rotating and driving the turn table 12; FIG. 16 is asectional view showing the state that the turn table 12 is mounted on adrive shaft 14 a of the motor 14; FIG. 17 is a plan view showing theturn table 12; FIG. 18 is a bottom view of the turn table 12; and FIG.19 is a plan view showing a plate spring 19 used here.

[0095] The turn table 12 is formed, in its centre portion, with acentring portion 40 so as to be projected upward, as shown in FIGS. 15and 16, similarly to that shown in the aforementioned embodiment. Thecentring portion 40 can be formed using synthetic resin, for example,such as polycarbonate, and as a material constituting the centringportion 40, any material may be used as long as it has quality not todemagnetize the magnetic force of the magnet 44.

[0096] The turn table 12 has a centring portion 40, a receiving portion46, a fixed portion 48, and a plurality of movable portions 50. Thesereceiving portion 46, fixed portion 48 and movable portions 50 areformed by integral molding. The centring portion 40 is provided with ashaft insert hole 442 a in which the drive shaft 14 a of the drive motor14 is pressed into the centre portion. The turn table 12 is mounted soas to be rotated integral with the drive shaft 14 a of the drive motor14 through the shaft insert hole 442 a.

[0097] The magnet 44 is mounted integrally in the centring portion 40 ofthe turn table 12. The magnet 44 is mounted so as to be buried in aconcave portion 40 a formed ringwise on the outer peripheral side on theextreme end side of the centring portion 40. That is, the magnet 44 ismounted by being insert-molded with respect to the centring portion 40.The magnet 44 can be insert-molded with respect to the centring portion40 because the centring portion 40 and the shaft portion 42 are formedof synthetic resin used normally without using a special syntheticmaterial which is a conventional creepless material. Moreover, since thecentring portion 40 and the shaft portion 42 are formed of a materialnot to demagnetize the magnetic force of the magnet 44, the magnet 44 isable to sufficiently hold its own magnetic force.

[0098] A metal plate 58 is provided on a chucking portion 56 for holdingthe optical disk D together with the turn table 12. The magnet 44magnetically attracts the metal plate 58 of the chucking portion 56, anda boss 59 of the chucking portion 56 is fitted into an engaging concaveportion 49 c provided in the centre portion on the upper end side of thecentring portion 40 whereby the chucking portion 56 presses the opticaldisk D against the receiving portion 46 of the turn table 12 forchucking.

[0099] The centring portion 40 formed into a convergent trapezoid isformed with a fixed portion 48 as shown in FIGS. 15 and 16. The fixedportion 48 is constituted by a part of a tapered outer peripheralportion of the centring portion 40. Further, for example, five movableportions 50 are formed at equal intervals around the outer peripheralportion of the centring portion 40.

[0100] The fixed portion 48 is a portion for supporting an innerperipheral edge 46 of a centre hole H of the optical disk D, as shown inFIG. 16, and the plurality of movable portions 50 have a centringfunction that it is formed as an elastically displaceable, orelastically movable, element long-cantilever supported along the outerperipheral surface of the centring portion 40 to be elasticallydisplaced to coincide the rotational centre of the optical disk D withthe centre shaft CL of the turn table 12.

[0101] Further, on the lower end side of the centring portion 40 isprovided a plate spring 460 as a return assisting member for returningthe movable portion 50 elastically deformed to an initial position. Forexample, the plate spring 460 has a function that in the state that itis formed, for example, from a thin metal sheet, and the optical disk Dis mounted on the movable portion 50, when the plate spring 60 iselastically deformed in a direction of arrow R1 in FIG. 16 together withthe movable portion 50, and the optical disk D is removed from the turntable 12, the movable portion 50 is forcibly returned in a direction ofarrow R2 in FIG. 16 so as to assume the initial state when the opticaldisk D is not mounted shown in FIG. 16.

[0102] The plate spring 460 used here is formed by punching a thinsheet-like metal plate formed of stainless steel (SUS301-CSP,SUS304-CSP) for a spring, or bronze for a spring (C5210P-1/2H) or thelike as shown in FIGS. 15 and 19. That is, the plate spring 460 isformed by punching a disk-like thin sheet metal plate by way of press, aplurality of, for example, five support elements 462 are projected atequal intervals around the outer peripheral portion of the ring-likeportion 61 bored with a centre hole 461 a, and a single detent element463 is projected.

[0103] The plate spring 460 used here also has a function that eachsupport element 462 elastically deformably supports the lower end of themovable portion 50 at a corresponding position. Each support element 462is formed substantially into the shape of T as shown in FIGS. 15 and 19.Further, one detent element 463 is formed between the support elements462, 462 adjacent to each other. The detent element 463 has a functionthat it is engaged with an engaging projection 400 projected on thelower end surface of the fixed portion 48 to thereby attain thedetention of the plate spring 460 with respect to the centring portion40. The plate spring 460 supports the lower end of the movable portion50 in the state that the engaging projection 400 is engaged with thedetent element 463. It is noted that the engaging projection 400 attainsanti-slipping of the detent element 463 by melting and deforming theextreme end thereof as necessary.

[0104] The turn table 12 having the thus formed plate spring 460 mountedthereon is mounted so as to be rotated integral with the drive shaft 14a by pressing the centre hole 461 a provided in the centre portion ofthe plate spring 460 and the shaft insert hole 42 a provided in thecentring portion 40 into the drive shaft 14 a of the drive motor 14.

[0105] The turn table used for rotating and driving the optical disk Dis formed with a plurality of fixed portions or fixed diametricalportions with which the centre hole H provided in the optical disk Dengages. The fixed portion (fixed diametrical portion) is formed in aproper diameter suppressing eccentricity with a centre hole of the turntable fitted in the drive shaft of the drive motor to be a rotationalcentre as a reference. In the turn table, in a case where volumeproduction is actually made, a working error occurs in the diameter ofthe centre hole, likely failing to attain accurate centring forcoinciding the rotational centre of the turn table with the rotationalcentre of the optical disk D when the optical disk D is mounted on theturn table.

[0106] In the present invention, the plate spring is provided in orderto absorb the working error of the turn table to accurately coincide therotational centre of the turn table with the rotational centre of theoptical disk D. The outer peripheral diameter of the movable portion forattaining the centring of the optical disk D provided in the centringportion is formed to be somewhat larger than a reference diameter of thecentre hole H of the optical disk D. By forming the movable portion asdescribed above, when the optical disk D is mounted, the centring forcoinciding the rotational centre with the rotational centre of the turntable is realized.

[0107] In the present invention, the movable portion for attaining thecentring of the optical disk D mounted with respect to the turn table isable to prevent occurrence of creep phenomenon caused by repetition offlexure deformation since the elastic return is assisted by the platespring. Since the creep phenomenon of the movable portion is suppressedby the plate spring, the turn table provided in the movable portion forcentring the optical disk can be formed of synthetic resin widely usedto attain the reduction in manufacturing cost.

[0108] It is noted that since the plate spring for applying the returnassisting forces to the movable portion for attaining the centring ofthe optical disk D used in the present invention can be basically formedinto a flat shape, the dimensional accuracy or the spring force isstabilized, and the operating reliance when the movable portion isreturned is high.

[0109] Since the turn table according to the present invention isprovided with the movable portion for attaining the centring of theoptical disk D mounted and the plate spring for applying the elasticforce to the movable portion, the centring portion can be pressed intocontact with the centre hole H of the optical disk D with the adequateelastic force, the vibration applied to the optical disk D when rotatedand driven can be absorbed to make the vibration resistance excellent.

[0110] Further, since the turn table shown in FIGS. 15 and 16 is mountedby the plate spring 460 into the drive shaft 14 a of the drive motor 14,the detention with respect to the drive shaft 14 a can be attained, andthe turn table can be integrated with the drive shaft 14 a positively.

[0111] Incidentally, in a case where the turn table 12 is mounted by theplate spring 60 into the drive shaft 14 a of the drive motor 14, asshown in FIGS. 20A and 20B, the press allowance of the turn table 12with respect to the drive shaft 14 a cannot be increased.

[0112] As shown in FIG. 20A, let F1 (N) be the re-press force of theturn table 12, and F2 (N) be the re-press force of the plate spring 60,then the re-press input F in a combination of both parts is F=F1+F2 asshown in FIG. 20B. The re-press force means the load resistance.

[0113] Even in a case where the press allowance of the turn table 12cannot be prolonged due to the presence of the dimensional restrictionin the height direction, the plate spring 60 is made of metal, and eventhin thickness, the sufficient re-press force, that is, the loadresistance can be obtained. Thereby, there is an advantage that ascompared with the use of only the turn table, when the plate spring isused, the load resistance increases.

[0114] Further, even in the turn table in which the plate spring issecured directly to the shaft portion provided integral with thecentring portion as shown in FIGS. 4 and 5, or in a case where the platespring is secured directly to the drive shaft of the drive motor, theplate spring is changed in position in the axial direction of the shaftportion or in the axial direction of the drive shaft whereby the supportelement of the plate spring is able to adjust the magnitude of thesupport force applied to the movable portion. The spring force appliedto the movable portion can be suitably changed according to the mountingposition of the plate spring.

[0115] Still another embodiment of the turn table 12 according to thepresent invention will be explained below with reference to FIGS. 21 to25.

[0116] As shown in FIG. 24, the plate spring 60 used here is formed bypunching a disk-like thin sheet metal plate by way of press or the like,a plurality of, for example, five support elements 62 are projected atequal intervals in a peripheral direction on the outer peripheral sideof the ring-like portion 61 bored with a centre hole 61 a, and a slippreventive portion support element 263 is formed between the supportelements 62. Each slip preventive portion support element 263 is formedin the middle portion with an engaging hole 263 a with which is engagedan engaging projection 100 projected on the bottom side of the centringportion 40. This plate spring 60 is mounted on the bottom surface of thecentring portion 46 by fitting the centre hole 61 a into the shaftportion 42 of the turn table 12, as shown in FIGS. 21 and 22. At thistime, the extreme end of the engaging projection 100 is thermallydeformed whereby the anti-slipping of the engaging hole 263 a from theengaging projection 100 is attained to prevent the plate spring 60 frombeing disengaged from the centring portion 40.

[0117] The support element 62 provided on the plate spring 60 is aportion for supporting the free end of the movable portion 50 providedin the centring portion 40, and the slip preventive portion supportelement 263 is a portion for supporting the slip preventive portion 69.The slip preventive portion 69 supported on the slip preventive portionsupport element 263 is molded by resin, for example, such as anelastomer. The slip preventive portion 69 is projected by a fixed amounton the place surface side of the optical disk D from a hole 99 providedin the turn table 12. The slip preventive portion 69 is formedsubstantially into the shape of U in section, as shown in FIGS. 21 and22, and is mounted so as to fit in the slip preventive portion supportelement 263 of the plate spring 60. FIG. 25 shows the slip preventiveportion 69, the hole 99 and so on, and FIG. 26 is a sectional view takenon line A-A of FIG. 25. The slip preventive portion 69 is mounted to beprojected in the direction of arrow Z in FIG. 26 from the hole 99 of theturn table 12, and the optical disk D is placed on the slip preventiveportion 69 as shown in FIG. 21.

[0118] The slip preventive portion 69 has a flange portion 69 aprojected on the outer peripheral surface engaged with an engagingconcave portion 99 a formed on the bottom side of the turn table 12 asshown in FIG. 26. Further, the slip preventive portion 69 has anengaging groove 69b formed in the outer peripheral surface on the baseend side engaged with the inner circumference of an engaging hole 263 bbored in the slip preventive portion support element 263 of the platespring 60. Thereby, the slip preventive portion 69 is held and securedbetween the turn table 12 and the plate spring 60.

[0119]FIG. 27 shows a further example of the slip preventive portion 69.A projection portion 69 d of the slip preventive portion 69 is insertedinto a hole 263 h provided in the slip preventive portion supportelement 263. A flange portion 69 e formed on the outer circumference ofthe slip preventive portion 69 is engaged with an engaging concaveportion 99 a formed on the bottom surface of the turn table 12. Thereby,the slip preventive portion 69 is held in the form sandwiched betweenthe turn table 12 and the plate spring 60.

[0120] The aforementioned slip preventive portion 69 has the followingfunction. That is, an upper surface 69 f of each slip preventive portion69 is slightly projected from the upper surface 46 a of the receivingportion 46 of the optical disk D. The upper surface 69 f of the slippreventive portion 69 supports the lower surface of the optical disk Dby way of the frictional force so that the optical disk D may not beslipped with respect to the turn table 12 at the time of rotation.

[0121]FIG. 23A is a plan view of the turn table 12 on which the slippreventive portion 69 is provided, and FIG. 23B is a bottom viewthereof.

[0122]FIG. 28 shows another embodiment of the turn table 12 according tothe present invention. The turn table 12 shown in FIG. 28 has the nearlysame construction as that shown in FIG. 22, but is different in shape ofa slip preventive portion 169. In the ensuing explanation, parts commonto those of the turn table shown in FIG. 22 are indicated by commonreference numerals, detailed explanation of which is omitted. The turntable 12 shown in FIG. 28 is mounted so as to be rotated integral withthe drive shaft 14 a by pressing the shaft insert hole 42 a of the shaftportion 42 provided integral with the centring portion 40 into the driveshaft 14 a of the drive motor 14.

[0123] A slip preventive portion 169 is mounted on the slip preventiveportion support element 163 of the plate spring 60 by way of fitting. Onthe upper surface of the slip preventive portion 169 is provided awaveform or concavo-convex type contact portion 169 g in order toprevent the optical disk from slipping. The slip preventive portion 169is provided so as to face to an opening 199 provided in the turn table12. The opening 199 has the size slightly larger than the slippreventive portion 169. The function of the slip preventive portion 169is nearly the same as that of the slip preventive portion 69 describedabove.

[0124]FIG. 29 shows still another embodiment of the turn table 12according to the present invention. The turn table shown in FIG. 29 ismounted so as to be rotated integral with the drive shaft 14 a bypressing an insert hole 40 h provided in the centre portion of thecentring portion 40 into the drive shaft 14 a of the drive motor 14.

[0125] The turn table shown in FIGS. 30 and 31 are common inconstitutional elements except the shaft portion and the plate spring60, detailed description of is therefore omitted.

[0126] A ring-like portion 261 in the centre portion of the plate spring60 shown in FIG. 31 has a concave portion 261 a in the central portionthereof. A small diameter portion 261 b is formed in the centre portionof the ring-like portion 261. The drive shaft 14 a of the drive motor 14shown in FIGS. 29 and 30 is pressed into the insert hole 261 b. Theplate spring 60 is directly pressed into the drive shaft 14 a of thedrive motor 14. The ring-like portion 261 has five support elements 62and five slip preventive portion support elements 63. The slippreventive portion support element 63 has an engaging hole 63 a, intowhich an engaging projection 100 shown in FIG. 29 is fitted. Theengaging projection 100 is deposited as necessary so that the platespring 60 is secured also to the centring portion 40 of the turn table12.

[0127] Since the turn table according to the present invention can beformed using a synthetic resin material excellent in rigidity andmolding accuracy, the turn table can be mounted on the drive shaft ofthe drive motor with high accuracy, and the optical disk can be mountedwith accurate centring. Further, since the movable portion for centringthe optical disk mounted is elastically biased by the plate spring, theoptical disk mounted is supported by the elastic force, thus providingthe great vibration proof effect with respect to the externalvibrations.

[0128] Further, in the present invention, color of the return assistingmember (plate spring) provided on the turn table and the slip preventiveportion is changed from color of other turn table portions, whereby theexternal design can be adjusted. Further, the return assisting memberand the slip preventive portion are coloured and the other portions ofthe turn table are transparent whereby the magnet inserted into thecentring portion can be viewed from the outside. The magnet is subjectedto the insert molding in the centring portion to thereby enablereduction in manufacturing cost and prevent the magnet from peeling offto enhance the mounting reliability.

[0129] Since the surface in contact with the optical disk of the slippreventive portion is formed to be higher than the upper surface of theturn table, that is, the place surface of the optical disk, the slippreventive effect of the optical disk is great as compared with the turntable manufactured in close contact with the optical disk surface and ofnormal quality by the friction force thereof, making use of elasticitysuch as rubber of elastomer.

[0130] The present invention is not limited to the aforementionedembodiments, but can be applied to not only the optical disk or theoptical magnetic disk but also other disk-like information recordingmedia.

[0131] Industrial Applicability

[0132] As described above, according to the present invention, there canbe manufactured easily and inexpensively a turn table capable ofrotating and driving accurately, when a disk-like recording medium ismounted, the medium while preventing eccentricity of the recordingmedium.

[0133] Further, there can be constituted a turn table capable ofrotating and driving a disk-like recording medium in the form ofaccurate integration.

1. (Amended) A turn table for mounting a disk-like information recordingmedium to rotate it continuously, comprising: a fixed portion fitted ina centre hole of said disk-like information recording medium; a movableportion fitted in said centre hole with said fixed portion as areference to be elastically deformed to correct eccentricity when saiddisk-like information recording medium is mounted; a shaft portionmolded integral with said fixed portion and into which is inserted adrive shaft of a motor for rotating said turn table continuously; and areturn assisting member secured to said shaft portion to return, whensaid disk-like information recording medium is not mounted, said movableportion from a position when said disk-like information recording mediumis mounted to a position when said disk-like information recordingmedium is not mounted, wherein said movable portion is an elasticdisplaceable element, a plurality of which are arranged at equal anglesabout a rotational centre shaft; wherein said return assisting member isa plate spring, a plurality of support elements are projected on theouter peripheral side of a ring-like portion bored with a centre hole,and each of said support elements elastically displaceably supports thelower end of the movable portion, corresponding to said elasticdisplaceable element of the movable portion.
 2. (Deleted)
 3. The turntable according to claim 1, further comprising: a member for chuckingsaid disk-like information recording medium, and a magnet for attractingsaid chucking member magnetically, said disk-like information recordingmedium being held between said magnet and said member for chuckingdetachably.
 4. (Amended) A turn table for mounting a disk-likeinformation recording medium to rotate it continuously, comprising: afixed portion having a hole for fitting a drive shaft of a motor forrotating said turn table continuously and fitted in a centre hole ofsaid disk-like information recording medium; a movable portion fitted insaid centre hole with said fixed portion as a reference to beelastically deformed to correct eccentricity when said disk-likeinformation recording medium is mounted; and a return assisting memberfor returning, when said disk-like information recording medium is notmounted, said movable portion from a position when said disk-likeinformation recording medium is mounted to a position when saiddisk-like information recording medium is not mounted, wherein saidmovable portion is an elastic displaceable element, a plurality of whichare arranged at equal angles about a rotational centre shaft; whereinsaid return assisting member is a plate spring, a plurality of supportelements are projected on the outer peripheral side of a ring-likeportion bored with a centre hole, and each of said support elementselastically displaceably supports the lower end of the movable portion,corresponding to said elastic displaceable element of the movableportion.
 5. (Deleted)
 6. The turn table according to claim 4, furthercomprising: a member for chucking said disk-like information recordingmedium, and a magnet for attracting said chucking member magnetically,said disk-like information recording medium being held between saidmagnet and said member for chucking detachably.
 7. (Amended) An opticaldisk device having a turn table for mounting a disk-like informationrecording medium to rotate it continuously, said turn table comprising:a fixed portion fitted in a centre hole of said disk-like informationrecording medium; a movable portion fitted in said centre hole with saidfixed portion as a reference to be elastically deformed to correcteccentricity when said disk-like information recording medium ismounted; and a shaft portion molded integral with said fixed portion andinto which is inserted a shaft of a motor for rotating said turn tablecontinuously, a return assisting member for returning, when saiddisk-like information recording medium is not mounted, said movableportion from a position when said disk-like information recording mediumis mounted to a position when said disk-like information recordingmedium is not mounted, wherein said movable portion is an elasticdisplaceable element, a plurality of which are arranged at equal anglesabout a rotational centre shaft; wherein said return assisting member isa plate spring, a plurality of support elements are projected on theouter peripheral side of a ring-like portion bored with a centre hole,and each of said support elements elastically displaceably supports thelower end of the movable portion, corresponding to said elasticdisplaceable element of the movable portion.
 8. (Deleted)
 9. The turntable according to claim 4, further comprising: a member for chuckingsaid disk-like information recording medium, and a magnet for attractingsaid chucking member magnetically, said disk-like information recordingmedium being held between said magnet and said member for chuckingdetachably.
 10. (Amended) An optical disk device having a turn table formounting a disk-like information recording medium to rotate itcontinuously, said turn table comprising: a fixed portion having a holefor fitting a shaft of a motor for rotating said turn table continuouslyand fitted in a hole in a centre hole of said disk-like informationrecording medium; a movable portion fitted in said centre hole with saidfixed portion as a reference to be elastically deformed to correcteccentricity when said disk-like information recording medium ismounted; and a return assisting member for returning, when saiddisk-like information recording medium is not mounted, said movableportion from a position when said disk-like information recording mediumis mounted to a position when said disk-like information recordingmedium is not mounted, wherein said movable portion is an elasticdisplaceable element, a plurality of which are arranged at equal anglesabout a rotational centre shaft; wherein said return assisting member isa plate spring, a plurality of support elements are projected on theouter peripheral side of a ring-like portion bored with a centre hole,and each of said support elements elastically displaceably supports thelower end of the movable portion, corresponding to said elasticdisplaceable element of the movable portion.
 11. (Deleted)
 12. The turntable according to claim 10, further comprising: a member for chuckingsaid disk-like information recording medium, and a magnet for attractingsaid chucking member magnetically, said disk-like information recordingmedium being held between said magnet and said member for chuckingdetachably.
 13. (Amended) A turn table for mounting a disk-likeinformation recording medium to rotate it continuously, comprising: afixed portion fitted in a centre hole of said disk-like informationrecording medium; a movable portion fitted in said centre hole with saidfixed portion as a reference to be elastically deformed to correcteccentricity when said disk-like information recording medium ismounted; a return assisting member for returning, when said disk-likeinformation recording medium is not mounted, said movable portion from aposition when said disk-like information recording medium is mounted toa position when said disk-like information recording medium is notmounted; and a slip preventive portion provided on said return assistingmember and coming into contact with said disk-like recording medium tothereby prevent said disk-like recording medium from slipping, whereinsaid movable portion is an elastic displaceable element, a plurality ofwhich are arranged at equal angles about a rotational centre shaft;wherein said return assisting member is a plate spring, a plurality ofsupport elements are projected on the outer peripheral side of aring-like portion bored with a centre hole, and each of said supportelements elastically displaceably supports the lower end of the movableportion, corresponding to said elastic displaceable element of themovable portion.
 14. An optical disk device having a turn table formounting a disk-like information recording medium to rotate itcontinuously, said turn table comprising: a fixed portion fitted in ahole in a centre hole of said disk-like information recording medium; amovable portion fitted in said centre hole with said fixed portion as areference to be elastically deformed to correct eccentricity when saiddisk-like information recording medium is mounted; a return assistingmember for returning, when said disk-like information recording mediumis not mounted, said movable portion from a position when said disk-likeinformation recording medium is mounted to a position when saiddisk-like information recording medium is not mounted; and a slippreventive portion provided on said return assisting member and cominginto contact with said disk-like recording medium to thereby preventsaid disk-like recording medium from slipping.